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Markham T. Puckett1, Ernest A. Mancini1, William C. Parcell1
(1) The University of Alabama, Tuscaloosa, AL

Abstract: Source rocks, maturation, and seals in carbonate systems of the Mississippi Interior salt basin

The Mississippi Interior Salt Basin (MISB) is the largest in a series of basins extending from southern Florida to east Texas that developed on thick transitional crust. A comprehensive study of the MISB has resulted in establishment of the stratigraphic framework (including formational tops, lithologic variations, thicknesses, and ages of the strata). This stratigraphic information was coupled with BHT, R0, TAI, TOC, and Tmax data to model the burial and thermal histories of the strata. Subsidence rates are greatest during the Jurassic and Early Cretaceous, and decrease in the Late Cretaceous and Cenozoic. Thermal modeling indicates that oil generation was initiated in the Early Cretaceous, and thermogenic natural gas generation commenced in the mid-Cretaceous and continued into the Tertiary. While the lower Smackover carbonates are the primary source rocks for the basin, Lower Cretaceous shales and carbonates are potential source rocks in the Perry sub-basin region. Carbonate reservoirs in the MISB occur in the Smackover Formation and, along the southern margin in the basin, the James Limestone, Mooringsport Formation, and Andrew Formation. Reef and/or shoal facies are the typical reservoir rocks. Anhydrites, such as the Buckner and those of the Rodessa Formation, cap many of the shoal facies of these carbonate units and form seals. Sequence stratigraphic analysis indicates that the petroleum source rocks typically occur in the condensed intervals, whereas the carbonate reservoir rocks, both reef and shoal facies, occur in the transgressive and highstand system tracts.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana